Now, this decible calculation has proven to be so useful, that occasionally they are applied to other units of measurement, instead of just watts. Specifically, the units "dBm" are used when the power unit being converted was in terms of milliwatts, not just watts. Let's say we have a value of 10dBm, we can go through the inverse calculation:

P=1010dBm/10=10mW{\displaystyle P=10^{10dBm/10}=10mW}

Likewise, let's say we want to apply the decibel calculation to a completely unrelated unit: hertz. If we have 100 Hz, we can apply the decibel calculation:

dB=10log⁡100Hz=20dBHz{\displaystyle dB=10\log {100Hz}=20dBHz}

If no letters follow the "dB" label, the decibels are referenced to watts.

Decibels are ratios, and are not real numbers. Therefore, specific care should be taken not to use decibel values in equations that call for gains, unless decibels are specifically called for (which they usually aren't). However, since decibels are calculated using logarithms, a few principles of logarithms can be used to make decibels usable in calculations.